Southeastern Asia: Island of Yapen in Indonesia

The Yapen Rain Forests [AA0108] are important for their two restricted-range bird species and unique limestone and ultramafic floras. Although almost one-third of the ecoregion is under some form of protection, the island is subject to population pressure.

Scientific Code

(AA0108)

Ecoregion Category

Australasia

Size

900 square miles

Status

Critical/Endangered

Habitats

Description Location and General DescriptionThis small ecoregion represents the lowland and montane rain forests of Yapen Island, off the northwestern coast of Irian Jaya, Indonesia, on the island of New Guinea. The climate of the ecoregion is tropical wet, which is characteristic of this part of Melanesia, located in the western Pacific Ocean north of Australia (National Geographic Society 1999). The surface geology of this ecoregion consists of low mountains of plutonic rock and limestone. The island extends to an elevation 1,430 m and is a land bridge island that was part of the New Guinea mainland during recent glacial periods.

The vegetation of Yapen Island is tropical lowland (alluvial and hill type) and montane forest.

Biodiversity FeaturesThe overall richness and endemism of this ecoregion are low to moderate when compared with those of other ecoregions in Indo-Malaysia.

An asterisk signifies that the species' range is limited to this ecoregion.

Yapen is home to approximately 147 bird species (Beehler et al. 1986; Coates 1985), including two restricted-range species that qualify it as a Secondary EBA. These two near-endemic species (table 2), the spice imperial-pigeon (Ducula myristicivora) and the green-backed robin (Pachycephalopsis hattamensis), are also found on the mainland (Stattersfield et al. 1998).

The island constitutes the Yapen Island Nature Reserve Centre of Plant Diversity (Davis et al. 1995). Several endemic plants have been collected, but the flora of the island is poorly known. The island contains significant limestone and ultramafic floras.

Justification of Ecoregion DelineationUsing Whitmore's (1984) map of the vegetation of Malesia and MacKinnon's (1997) reconstruction of the original vegetation, we delineated the large areas of distinct habitat types as ecoregions. Yapen and Biak islands, which MacKinnon combined within biounit P3c, were delineated as separate ecoregions; Yapen Rain Forests [AA0108] and Biak-Numfoor Rain Forests [AA0103], respectively, were based on recommendations by Bob Johns (vegetation) and the patterns of mammal distribution. Udvardy (1975) placed these ecoregions in the Papuan biogeographic province of the Oceanian Realm.

ReferencesReferences for this ecoregion are currently consolidated in one document for the entire Indo-Pacific realm.Indo-Pacific Reference List

Prepared by: John MorrisonReviewed by:

This text was originally published in the book Terrestrial ecoregions of the Indo-Pacific: a conservation assessment from Island Press. This assessment offers an in-depth analysis of the biodiversity and conservation status of the Indo-Pacific's ecoregions.